FIELD OF THE INVENTION
The invention relates to a pyrolytic self-cleaning process for stoves having a muffle being operable by means of a fold-down heating element disposed in at least one wall region and having additional ambient air heating, the muffle being ventilatable by an ambient air blower and being equipped with means for pyrolytic self-cleaning, and a sensor array disposed in the cooking chamber for detecting oven soiling values being dictated by operation.
German Patents DE-PS 21 66 227 and 23 10 290 disclose stove muffles with means for pyrolytic self cleaning. The point of departure there is that for pyrolytic self-cleaning, mean oven temperatures above 500.degree. C. must be employed to achieve satisfactory self-cleaning effects. Temperatures of approximately 500.degree. C. are maintained for a certain period of time, and this period corresponds to a value ascertained by trial and error, rather than reproducing the actual conditions of muffle soiling.
However, more recent tests have confirmed that temperatures of approximately 450.degree. C. in the center of the oven have an adequate pyrolytic self-cleaning effect. The relatively long-chained molecules of the soiling adhering to the walls of the muffle are subjected to thermal cracking by long-persisting heating to above 450.degree. C., and thus are converted into relatively short-chained products of decomposition, such as water, short hydrocarbons, aromatics, and ash residues. The gaseous products of decomposition are removed from the stove by venting during the self-cleaning. Once the self-cleaning is completed, the remaining residues, in the form of ash, can be removed from the stove. Along the way to 450.degree. C. at the center of the oven, temperature ranges are traversed that promote increased carbon monoxide development. Such toxic, unwelcome gas may be considered harmless for temperatures above 450.degree. C. in terms of its concentration that is capable of escaping to the outside. Many manufacturers have therefore attempted to perform heating as quickly as possible to a temperature above 450.degree. C. in the muffle and to start the long-term pyrolysis process only after that. On the other hand, experiments have shown that valuable enamel in stoves of the upper price category, for which self-cleaning processes are offered, is involved to the point of destruction by the action of heat at approximately 500.degree. C.